Burr

The situation that board surface or edge is not smooth because of irregular routing.
There are "copper burr", "glass cloth burr", "resin burr", etc.

Copper burr

Glass cloth burr

Router Bit Design

Cause Failure condition Countermeasure
Large thrust force. Too large upward force acting on the board causes burr on the surface of the board. Use entry board.
Use a router with small helix angle.
Use a router which has left hand, down draft geometry.
Heavy wear. When the wear is increased, the cutting edges lose their sharpness and burr occurs on the board. Change to the new router.
Reduce spindle speed and increase feed rate (unless breakage is not happened).

Routing Parameter

Cause Failure condition Countermeasure
Fast feed rate. Fast feed rate causes large force lifting up the boards, and burr occurs easily. Reduce feed rate.
High spindle speed, slow feed rate. This condition hastens the cutting edge wear. In this situation burr occurs easily by the dull cutting edge. Reduce spindle speed and increase feed rate (unless breakage is not happened).

PCB Setting

Cause Failure condition Countermeasure
Board material, composition. Because of the hardness of board or adhesional strength of layer, there are some materials that burr occurs easily. Use entry board.
If necessary, add the finish routing.
Opening between the stack of the boards. If there is opening between the two boards, burr occurs to the space easily. Set the boards on the work table firmly not to make the opening between the boards (check the stud pins).
Moving of the boards. If fixed inadequately, boards may move and become some opening between the boards. In this case, burr occurs to the space easily. Fix the boards on the work table rigidly (check the stud pins and the fix tape).

Equipment

Cause Failure condition Countermeasure
Large spindle runout. The rotation of the router becomes unstable and burr occurs easily. Repair the spindle (collet).

PRODUCT 01 PCB Drills / Routers / Ultra precision micro-hole drill

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